The present invention relates to a complex composition of styrene-based block copolymer and PBT resin and, more particularly, to a complex composition of styrene-elastomer block copolymer and PBT resin that uses a mixture of polystyrene-elastomer block copolymer (TPR), paraffin oil and polybutylene terephthalate (PBT) resin to compensate for the unfavorable factors of thermoplastic rubber (TPR), that is, the defects of properties, such as weather resistance, thermal resistance, oil resistance, adhesiveness, and printability, etc., and to improve processability.
Polyvinyl chloride (PVC) is the most widely used synthetic resin due to its excellences in processability and properties, including weather resistance, tensile strength, elongation, scratch hardness, adhesiveness, abrasion resistance, etc. Particularly, soft PVC is a resin most widely used for vinyl leather, tarpaulin, films or sheets, injection molded products, extruded products, etc. Recently, the toxic properties of plasticizers on the human body and the environmental issues of the PVC resin have imposed prohibition or restriction on the use of PVC products. Yet, the PVC products are still widely used as a subsidiary material for bags, materials for construction or advertisement, and so forth.
In particular, when the PVC resin is used in combination with fabrics like artificial leather or tarpaulin, its waste is disposed through incineration to cause environmental and cost problems. The styrene-based block copolymer (thermoplastic rubber (TPR)), such as SBS, SEBS, SIS, SEPS, etc., substitute most of cured rubber or soft PVC, but it cannot be used as a complete constitute due to its defects of properties, including weather resistance, thermal resistance, oil resistance, adhesiveness, printability, etc.
As a solution to this problem, the styrene-based block copolymer is mixed with the PBT resin with good properties to enhance the properties so that it can be used as a more popular substitute for the soft PVC.
Generally, SBS is mixed with a process oil like paraffin oil or another resin, such as polystyrene (PS), polyethylene (PE), polypropylene (PP), etc., subjected to compounding (cutting after extrusion) and then primarily used as a material for injection molded products.
The SBS has the same favorable factors as rubber with good properties like cold resistance, elasticity, water resistance, and processability, but it is poor in oil resistance, weather resistance, abrasion resistance, and thermal resistance and displays poor extrusion processability. In order to compensate for this shortness, it is expected to improve when mixed with the PBT resin that has good properties and relatively good compatibility with the styrene-based block copolymer.
The background technique of the present invention is KR Registered Patent Publication No. 1004614 under the title of “PETG-based decor sheet for moulding that has similar moldability to PVC” (Patent Document 1). The background technique suggests a decor sheet comprising a PETG alloy resin prepared by alloying a polyethylene terephthalate glycol (PETG) resin with an elastomer resin, where the elastomer resin is a copolymer of a polybutylene terephthalate (PBT) resin and polyether glycol.
But, the prior technique provides a similar moldability to the PVC and is available for hard sheets and containers, yet it encounters a difficulty in the production of soft films or soft sheets because it is hard of softening.